The present invention is used in construction machines for processing ground or road surfaces, especially in a milling machine for milling road and ground surfaces, in a stabilizer for stabilizing ground of low bearing capacity and in a recycler for repairing pavements in need of repair. A generic construction machine is known for example from EP 0 960 239 B1. Such construction machines are provided with a working roller, with which the ground or the road surface can be broken open and/or thoroughly mixed. If processing relates to an asphalt or concrete road surface, a typical working process is milling off the road surface. The working roller is held horizontally with respect to its cylinder axis directly or indirectly on a machine frame of the construction machine and extends transversely to the longitudinal direction of the construction machine. The working roller is covered by a protective hood that encloses a working chamber in its interior in which the working roller will rotate in working operation. The working chamber is open towards the ground, so that the working roller can come into contact with the ground to be processed. The hood thus prevents the material milled off by the working roller rotating about its longitudinal axis from being ejected in an uncontrolled manner into the ambient environment of the construction machine. The working chamber, which is externally delimited by the hood, is further used for material transport in order to enable the removal of the material milled off by the milling roller in a controlled manner for example. It can be a further application of the working chamber to use said chamber as a mixing chamber in which the processed ground material can be mixed with an additive in order to achieve fixing or stabilization of the ground. Typical additives are hydraulic or bituminous bonding agents or water for example.
For this reason, a generic construction machine comprises a spraying device, with which a fluid can be introduced into the working chamber of the construction machine. The spraying device comprises at least one outlet nozzle for this purpose, through which the fluid is introduced into the working chamber. Furthermore, a line system is provided via which the fluid is guided to the at least one outlet nozzle. A further important element is finally a control unit, by means of which the fluid supply to the outlet nozzle can be controlled. The control unit thus represents the central control component of the spraying device and is responsible for the control of the spraying device and the individual components of the spraying device. The control unit can comprise a respectively programmed microcontroller for example which triggers the respective components of the spraying device by way of suitable signal connections. Typical control functions are the activation and deactivation of the fluid supply for example, the regulation of the fluid pressure and the fluid quantity per unit of time which exits through the at least one outlet nozzle, the type of fluid, etc.
It is possible to introduce fluid from the outside into the interior of the protective hood or the working chamber via the at least one outlet nozzle. The construction machine comprises a respective line system for this purpose which guides the fluid to the at least one outlet nozzle. The line system can comprise one or several respective fluid storage reservoirs for this purpose, for example, which are arranged to be integrated in the construction machine. It is alternatively possible to ensure the supply with fluid via a respective supply vehicle such as a tanker truck that is connected to the line system of the construction machine and moves together with the operational construction machine. The line system can optionally comprise further components such as one or several pumps, via which the fluid is pumped from the storage reservoir to the line system and finally to the at least one outlet nozzle, filter, etc.
A typical application in which the introduction of a fluid into the working chamber of the construction machine is desired is the mixture of the material processed by the working roller in the working chamber with water in order to achieve improved material properties of the ground material together with bonding agents previously applied to the ground to be processed such as lime for example. Alternatively, the formation of dust during processing can also be reduced by wetting the ground material for example. Further exemplary applications are the introduction of bituminous bonding agents, the production and introduction of foamed bitumen, etc.
It has been noticed in practical application of such construction machines with a spraying device that the at least one outlet nozzle of the spraying device is frequently clogged by the processed material. This prevents any further controlled introduction of a fluid into the working chamber. This is especially unsatisfactory for the reason that the cleaning of the at least one outlet nozzle is comparatively time-consuming and causes long standstill times for the construction machine.
A modified outlet nozzle with a triggerable closing device is known for this reason from DE 102 41 067 B3, by means of which a journal can be moved into the outlet nozzle in order to enable the ejection of material present in the at least one outlet nozzle and to achieve free passage in the at least one outlet nozzle. As long as the outlet nozzle is not in operation, the opening of the outlet nozzle can be further sealed with the journal so that no ground material can penetrate the outlet nozzle. The closing device as described there for an outlet nozzle has a comparatively complex configuration and comprises a plurality of movable and immovable parts, so that it requires a fair amount of maintenance work. Moreover, the spraying device as described there represents a considerable cost factor as a result of its complexity.
It is therefore the object of the invention to improve the spraying device of a generic construction machine in the respect that it effectively prevents the clogging of the at least one outlet nozzle in a simple and comparatively cost-effective manner and especially requires a low amount of maintenance at the same time.